The present invention generally relates to an internal combustion engine having a multilink-type piston crank mechanism for reciprocating a piston.
Japanese Patent Application Publication No. 2001-227367 discloses a variable compression ratio mechanism of an internal combustion engine using a multilink piston crank mechanism, which was previously proposed by the assignee of the present application. This mechanism links a piston and a crankpin with each other by an upper link and a lower link. One end of the upper link is connected with the piston via a piston pin. The other end of the upper link is connected with the lower link via a first connection pin. The lower link is mounted rotatably on the crankpin of a crankshaft. Moreover, this mechanism restrains movement of the lower link by a control link having one end connected with the lower link via a second connection pin. The other end of the control link is supported on a lower part of a cylinder block via a cam mechanism. The center of swinging motion of the other end of the control link can be shifted by the cam mechanism so as to vary a top dead center of the piston.